Index all addon records, and allow public addons to the public.

[kloor]

We discovered two issues with addon records. First, if a single addon record was created or updated it would only be indexed if it was public. Second, public users could not see addons in the search results. This patch fixes both of those issues.

The change to lib/SolrSearch/Addon/Manager.php will index all addon records regardless to if they are public or not.

The changes to lib/SolrSearch/Addon/Indexer.php make sure that the public field is set on the addon record's document, instead of that field always being null. This allows the public to see those records. The isRecordIndexed method is changed to isRecordPublic to match its new role in setting the public field. The _addFlag method is removed as it is made redundant to checks against the public field.